Goods receipt item availability

Hello,

we use transaction VA01 to create sales orders. When we do not have stock of the article we sell to our customer, we create a purchase order with transaction ME21N. There is no direct link with the sales order, however we enter the sales order number as text in the purchase order.

When there is a good receipt we would like to know which orders are now ready to deliver. Is there a transaction which shows you which orders have not yet been delivered, but are ready to be delivered after the roods receipt has been booked?